diff --git a/app/lib/link_details_extractor.rb b/app/lib/link_details_extractor.rb
index cf273e4967d59e..6fa4338c70f4a1 100644
--- a/app/lib/link_details_extractor.rb
+++ b/app/lib/link_details_extractor.rb
@@ -232,14 +232,6 @@ def valid_url_or_nil(str, same_origin_only: false)
     nil
   end
 
-  def valid_locale_or_nil(str)
-    return nil if str.blank?
-
-    code,  = str.split(/_-/) # Strip out the region from e.g. en_US or ja-JA
-    locale = ISO_639.find(code)
-    locale&.alpha2
-  end
-
   def link_tag(name)
     document.xpath("//link[@rel=\"#{name}\"]").map { |link| link['href'] }.first
   end
diff --git a/spec/helpers/languages_helper_spec.rb b/spec/helpers/languages_helper_spec.rb
index 6db617824db8f8..b455cee33d1a3a 100644
--- a/spec/helpers/languages_helper_spec.rb
+++ b/spec/helpers/languages_helper_spec.rb
@@ -3,9 +3,9 @@
 require 'rails_helper'
 
 describe LanguagesHelper do
-  describe 'the HUMAN_LOCALES constant' do
-    it 'includes all I18n locales' do
-      expect(described_class::HUMAN_LOCALES.keys).to include(*I18n.available_locales)
+  describe 'the SUPPORTED_LOCALES constant' do
+    it 'includes all i18n locales' do
+      expect(Set.new(described_class::SUPPORTED_LOCALES.keys + described_class::REGIONAL_LOCALE_NAMES.keys)).to include(*I18n.available_locales)
     end
   end